Thorium-230

Thorium-230 is a radioactive type of metal. It's also known as Ionium. It's symbol, according to Iodium was Io. It's first know use was in 1907. It has 90 protons, 90 electrons, and 140 neutrons. It's half life, which is the amount of time it takes half of the atoms to decay, is over 80,000 years. This isotope is naturally produced. Thorium-230 is used to determine the sedimentation rates in the oceans. It's in seawater, produced by the decaying of uranium-234. Thorium-230 is very abundant, it exceeds the equilibrium amount. 

This is the Bohr Model of Thorium-230.

The team of UNC takes short cores to determine sedimentation rates into the North Carolina coastal system through geochemical dating methods. Faculty and students work together within the multidisciplinary research department of Marine Sciences to solve issues along the coastal zone. to read more, visit: http://www.unc.edu/spotlight/of-beaches-and-barrier-islands/

Sources: 
http://ie.lbl.gov/toi/nuclide.asp?iZA=900230
http://www.periodni.com/download/periodic_table-color.png
http://www.britannica.com/EBchecked/topic/293005/ionium-thorium-dating#ref218826
http://www.britannica.com/EBchecked/topic/152243/dating/69779/Uranium-series-disequilibrium-dating#ref584970
http://www.unc.edu/spotlight/of-beaches-and-barrier-islands/